CHANGES IN ALVEOLAR-CAPILLARY FORMATION IN GROWING RAT LUNG BY REPEATED INJECTIONS OF A LATHYROGEN

We hypothesized that abnormal capillary formation, which might be asso ciated with an alteration in extracellular malular matrix (ECM), occur s in the alveoli of growing rat lungs treated with beta-aminopropionit rile (beta APN), a lathyrogen that inhibits lysyl oxidase activity. On scanning electron microscopy, a corrosion cast of alveolar capillarie s in lungs treated with beta APN appeared abnormal in configuration; t ransmission electron microscopy showed extensive morphological changes in interstitial cells and ECMs, including collagen, elastin, and pres umably glycosaminoglycans and, in binding water (GBW). Morphometric da ta revealed an increase in GBW of up to 24.4%, a decrease in the amoun t of collagen fiber (44.5%), and a decrease in lipid-laden interstitia l cells; however, the change in elastin was limited to morphological a ppearance. From these observations, we conclude that alterations in al veolar capillary formation are associate with extensive changes in ECM s, and that these changes in ECM components might also be involved in the abnormal alveolar formations induced by beta APN.